<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    .content {
        height: 200px;
        width: 100%;
        display: flex;
        background: yellow;
    }
    .left {
        width: 100px;
        height: 100%;
        background: red;
    }
    .right {
        height: 100%;
        flex: 1;
        background: green;
    }
</style>

<body>
    <div class="content">
        <div class="left">

        </div>
        <div class="right">

        </div>
    </div>
</body>

</html>